.circle{
    display: flex;
    flex-wrap: wrap;
    max-width: 645px;
}
.circle div{
    margin: 10px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    /* background: #000; */
    border: 1px solid red;
    color: white;
    text-align: center;
    line-height: 50px;
}
.circle div:nth-of-type(2n+1){
    background: blue;
}
.circle div:nth-of-type(2n){
    background: black;
}
